Tear film break-up time

Method

Interval between a complete blink and the first break in the tear film, by slit-lamp observation after fluorescein instillation, or without fluorescein where a non-invasive method is used. Which method is recorded on the edge, since the two give systematically different values.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

6 papers, 5 randomised. RISING is improvement — a longer interval before the film breaks. A clinical SIGN, distinct from the symptom questionnaire reported alongside it; the two disagree often enough in the same eyes that treating them as one endpoint would be wrong.